Retailers focusing on loss prevention (e.g. theft) traditionally have three approaches to minimize loss: (1) anchoring the merchandise in place (e.g., attaching cables to the merchandise, putting articles in display cases and behind the counter); (2) using video surveillance systems and/or security guards to watch everyone in the store; and (3) using an alarm system with special tags attached to items that sounds off an alarm whenever a shoplifter tries to leave with a tagged item. Anchoring the merchandise in place makes it difficult for shoppers to examine items and try on garments. Customers have to wait for a clerk to release the item so the customer can try it on or look at it. This inconvenience motivates shoppers to shop at stores where the merchandise is more accessible. In addition, anchoring merchandise is costly as a store must provide labor just to release the merchandise. Video surveillance systems including monitoring devices, observation mirrors and security cards were among the earliest approaches to combat shoplifting. However, the cost of labor is expensive and the surveillance systems can be intrusive, especially in areas (e.g. dressing rooms) where shoppers would prefer some level of privacy.
Radio frequency (RF) Tagging security systems are useful anywhere there is an opportunity for theft of items of any size. Using tagging technology (e.g., electronic article security (EAS), radio frequency identification (RFID)) enables a retailer to display popular items on the floor, where they can be seen, rather than putting them in locked cases or behind the counter. The use of EAS and RFID systems for detecting and preventing theft or unauthorized removal of articles or goods from facilities has become widespread. In general, such systems have RF antennas that detect resonant tags attached to articles in a security or detection zone of the antennas. Such systems are generally located at or around points of exit to detect the security tag, and thus the article, as it transits through the exit point.
EAS systems are limited by the capabilities of their tags. Unfortunately, EAS tags contain no information. They are simply there or not there. Tag systems designed to add information to RF tags use radio frequency identification (RFID) technologies to read information from RFID tags. RFID tags can store information about the product as well as uniquely identify each of the products. Unfortunately, RFID systems encounter problems of obstruction or improper disorientation. In RFID technology, antennas and tags communicate with each other along a line of sight as antennas send integration signals and read response signals from the tags. RFID signals are blocked, absorbed or reflected or otherwise modified by conductive objects, including people. An RFID tag passing through a sensor net or detection zone of RFID antennas may not be detected by the antennas if the direct path between the tag and antennas is blocked. That is, a person can easily hide a tag so that it is not seen (e.g., read, detected) by the RFID system. The person hiding the tag can walk through the RFID system's detection zones without sounding an alarm and the system has no way to locate the loss tag or its associated article. If a RFID tag is hidden, it can not be identified or tracked with known tagging systems. A possible approach is combining the RFID system with a video surveillance system, which could follow a person associated with a hidden or lost tag in real-time. However, this approach is expensive and invasive. Accordingly, there is a need for systems which can non-invasively track tagged products regardless of whether the tag can be seen. Moreover, it would beneficial to provide a system that could non-invasively identify and track moving objects without video surveillance.
Warehouses are using RF tagging technology with resonant tags located in the floor and matrix portable readers on forklifts for inventory purposes. Automotive vehicle systems have used RF tagging technology with resonant tags embedded in the road to help steer vehicles. As a vehicle travels down a road, an antenna on the vehicle identifies the embedded tags as markers to approach or stay to one side of to help the vehicle stay in a lane. However, neither of these approaches has solved the need to non-invasively identify and track moving objects.